Imaging systems with high dynamic range and phase detection pixels

ABSTRACT

A pixel may include an inner sub-pixel group and an outer sub-pixel group. The inner sub-pixel group may have a smaller light collecting area than the outer sub-pixel group and therefore be less sensitive to light than the outer sub-pixel group. This may enable the pixel to be used to generate high dynamic range images, even with the sub-pixel groups using the same length integration time. The inner sub-pixel group may be nested within the outer sub-pixel group. Additionally, one or both of the inner sub-pixel group and the outer sub-pixel group can be split into at least two sub-pixels so that the sub-pixel group can be used to gather phase detection data. Adjacent pixels may have sub-pixel groups split in different directions to enable detection of vertical and horizontal edges in a scene.

This application is a division of U.S. patent application Ser. No.15/184,170, filed Jun. 16, 2016, which is hereby incorporated byreference herein in its entirety. This application claims the benefit ofand claims priority to U.S. patent application Ser. No. 15/184,170,filed Jun. 16, 2016.

BACKGROUND

This relates generally to imaging systems and, more particularly, toimaging systems with high dynamic range functionalities and phasedetection capabilities.

Modern electronic devices such as cellular telephones, cameras, andcomputers often use digital image sensors. Imager sensors (sometimesreferred to as imagers) may be formed from a two-dimensional array ofimage sensing pixels. Each pixel receives incident photons (light) andconverts the photons into electrical signals. Image sensors aresometimes designed to provide images to electronic devices using a JointPhotographic Experts Group (JPEG) format.

Some applications such as automatic focusing and three-dimensional (3D)imaging may require electronic devices to provide stereo and/or depthsensing capabilities. For example, to bring an object of interest intofocus for an image capture, an electronic device may need to identifythe distances between the electronic device and object of interest. Toidentify distances, conventional electronic devices use complexarrangements. Some arrangements require the use of multiple imagesensors and camera lenses that capture images from various viewpoints.Other arrangements require the addition of lenticular arrays that focusincident light on sub-regions of a two-dimensional pixel array. Due tothe addition of components such as additional image sensors or complexlens arrays, these arrangements lead to reduced spatial resolution,increased cost, and increased complexity.

Conventional imaging systems also may have images with artifactsassociated with low dynamic range. Scenes with bright and dark portionsmay produce artifacts in conventional image sensors, as portions of thelow dynamic range images may be over exposed or under exposed. Multiplelow dynamic range images may be combined into a single high dynamicrange image, but this typically introduces artifacts, especially indynamic scenes.

It would therefore be desirable to be able to provide improved imagingsystems with high dynamic range functionalities and depth sensingcapabilities.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an illustrative electronic device withan image sensor that may include phase detection pixels in accordancewith an embodiment of the present invention.

FIG. 2A is a cross-sectional side view of illustrative phase detectionpixels having photosensitive regions with different and asymmetricangular responses in accordance with an embodiment of the presentinvention.

FIGS. 2B and 2C are cross-sectional views of the phase detection pixelsof FIG. 2A in accordance with an embodiment of the present invention.

FIG. 3 is a diagram of illustrative signal outputs of photosensitiveregions of depth sensing pixels for incident light striking the depthsensing pixels at varying angles of incidence in accordance with anembodiment of the present invention.

FIG. 4 is a top view of an illustrative pixel with an inner sub-pixeland an outer sub-pixel that is covered by a toroidal microlens inaccordance with an embodiment of the present invention.

FIG. 5 is a top view of an illustrative pixel with an inner sub-pixeland a split outer sub-pixel group that is covered by a toroidalmicrolens in accordance with an embodiment of the present invention.

FIG. 6 is a cross-sectional bottom view of the front side of anillustrative pixel with an inner sub-pixel and a split outer sub-pixelgroup in accordance with an embodiment of the present invention.

FIG. 7 is a cross-sectional top view of the backside of the illustrativepixel of FIG. 6 in accordance with an embodiment of the presentinvention.

FIG. 8 is a top view of an illustrative pixel with an inner sub-pixeland a split outer sub-pixel group that is covered by a circularmicrolens in accordance with an embodiment of the present invention.

FIG. 9 is a top view of an illustrative pixel with an inner sub-pixeland a split outer sub-pixel group that is covered by four circularmicrolenses in accordance with an embodiment of the present invention.

FIG. 10 is a top view of an illustrative pixel with an inner sub-pixeland a split outer sub-pixel group that is covered by two ellipticalmicrolenses in accordance with an embodiment of the present invention.

FIG. 11 is a top view of an illustrative pixel with an inner sub-pixeland vertically oriented outer sub-pixels that is covered by a toroidalmicrolens in accordance with an embodiment of the present invention.

FIG. 12 is a top view of an illustrative pixel with an inner sub-pixeland a diagonally split outer sub-pixel group that is covered by atoroidal microlens in accordance with an embodiment of the presentinvention.

FIG. 13 is a top view of an illustrative pixel with a split innersub-pixel group and an outer sub-pixel that is covered by a toroidalmicrolens in accordance with an embodiment of the present invention.

FIG. 14 is a top view of an illustrative pixel with a split innersub-pixel group and a split outer sub-pixel group that is covered by atoroidal microlens in accordance with an embodiment of the presentinvention.

FIG. 15 is a top view of an illustrative pixel with a split innersub-pixel group and a split outer sub-pixel group that is split in adifferent orientation than the inner sub-pixel group in accordance withan embodiment of the present invention.

FIG. 16 is a top view of an illustrative pixel with a split outersub-pixel group and an inner sub-pixel that is partially covered by ashielding layer in accordance with an embodiment of the presentinvention.

FIG. 17 is a top view of illustrative pixels with two sub-pixelsarranged in a 2×2 repeating unit cell in accordance with an embodimentof the present invention.

FIG. 18 is a top view of illustrative pixels with two sub-pixelsarranged in a 2×4 repeating unit cell in accordance with an embodimentof the present invention.

FIG. 19 is a top view of illustrative pixels with an outer sub-pixelgroup that surrounds an inner sub-pixel that are arranged in a 2×2repeating unit cell in accordance with an embodiment of the presentinvention.

FIG. 20 is a top view of illustrative pixels with an outer sub-pixelgroup that surrounds an inner sub-pixel that are arranged in a 2×4repeating unit cell in accordance with an embodiment of the presentinvention.

FIG. 21 is a top view of illustrative pixels with an outer sub-pixelgroup that surrounds an inner sub-pixel group that are arranged in a 2×2repeating unit cell in accordance with an embodiment of the presentinvention.

FIG. 22 is a top view of illustrative pixels arranged in a 2×4 repeatingunit cell where shielding layers cover portions of inner sub-pixels inaccordance with an embodiment of the present invention.

FIG. 23 is a top view of illustrative pixels arranged in a 2×2 repeatingunit cell where shielding layers cover portions of inner sub-pixels inaccordance with an embodiment of the present invention.

FIG. 24 is a top view of illustrative pixels arranged in a 2×4 repeatingunit cell where shielding layers cover portions of inner sub-pixels inaccordance with an embodiment of the present invention.

DETAILED DESCRIPTION

Embodiments of the present invention relate to image sensors with highdynamic range (HDR) functionalities and depth sensing capabilities. Anelectronic device with a digital camera module is shown in FIG. 1.Electronic device 10 may be a digital camera, a computer, a cellulartelephone, a medical device, or other electronic device. Camera module12 (sometimes referred to as an imaging device) may include image sensor14 and one or more lenses 28. During operation, lenses 28 (sometimesreferred to as optics 28) focus light onto image sensor 14. Image sensor14 includes photosensitive elements (e.g., pixels) that convert thelight into digital data. Image sensors may have any number of pixels(e.g., hundreds, thousands, millions, or more). A typical image sensormay, for example, have millions of pixels (e.g., megapixels). Asexamples, image sensor 14 may include bias circuitry (e.g., sourcefollower load circuits), sample and hold circuitry, correlated doublesampling (CDS) circuitry, amplifier circuitry, analog-to-digital (ADC)converter circuitry, data output circuitry, memory (e.g., buffercircuitry), address circuitry, etc.

Still and video image data from image sensor 14 may be provided to imageprocessing and data formatting circuitry 16 via path 26. Imageprocessing and data formatting circuitry 16 may be used to perform imageprocessing functions such as automatic focusing functions, depthsensing, data formatting, adjusting white balance and exposure,implementing video image stabilization, face detection, etc. Forexample, during automatic focusing operations, image processing and dataformatting circuitry 16 may process data gathered by phase detectionpixels in image sensor 14 to determine the magnitude and direction oflens movement (e.g., movement of lens 28) needed to bring an object ofinterest into focus.

Image processing and data formatting circuitry 16 may also be used tocompress raw camera image files if desired (e.g., to Joint PhotographicExperts Group or JPEG format). In a typical arrangement, which issometimes referred to as a system on chip (SOC) arrangement, camerasensor 14 and image processing and data formatting circuitry 16 areimplemented on a common integrated circuit. The use of a singleintegrated circuit to implement camera sensor 14 and image processingand data formatting circuitry 16 can help to reduce costs. This is,however, merely illustrative. If desired, camera sensor 14 and imageprocessing and data formatting circuitry 16 may be implemented usingseparate integrated circuits. If desired, camera sensor 14 and imageprocessing circuitry 16 may be formed on separate semiconductorsubstrates. For example, camera sensor 14 and image processing circuitry16 may be formed on separate substrates that have been stacked.

Camera module 12 may convey acquired image data to host subsystems 20over path 18 (e.g., image processing and data formatting circuitry 16may convey image data to subsystems 20). Electronic device 10 typicallyprovides a user with numerous high-level functions. In a computer oradvanced cellular telephone, for example, a user may be provided withthe ability to run user applications. To implement these functions, hostsubsystem 20 of electronic device 10 may include storage and processingcircuitry 24 and input-output devices 22 such as keypads, input-outputports, joysticks, and displays. Storage and processing circuitry 24 mayinclude volatile and nonvolatile memory (e.g., random-access memory,flash memory, hard drives, solid state drives, etc.). Storage andprocessing circuitry 24 may also include microprocessors,microcontrollers, digital signal processors, application specificintegrated circuits, or other processing circuits.

It may be desirable to provide image sensors with high dynamic rangefunctionalities (e.g., to use in low light and high light environmentsto compensate for high light points of interest in low lightenvironments and vice versa). To provide high dynamic rangefunctionalities, image sensor 14 may include high dynamic range pixels.

It may be desirable to provide image sensors with depth sensingcapabilities (e.g., to use in automatic focusing applications, 3Dimaging applications such as machine vision applications, etc.). Toprovide depth sensing capabilities, image sensor 14 may include phasedetection pixel groups such as phase detection pixel group 100 shown inFIG. 2A. If desired, pixel groups that provide depth sensingcapabilities may also provide high dynamic range functionalities.

FIG. 2A is an illustrative cross-sectional view of pixel group 100. InFIG. 2A, phase detection pixel group 100 is a pixel pair. Pixel pair 100may include first and second pixels such Pixel 1 and Pixel 2. Pixel 1and Pixel 2 may include photosensitive regions such as photosensitiveregions 110 formed in a substrate such as silicon substrate 108. Forexample, Pixel 1 may include an associated photosensitive region such asphotodiode PD1, and Pixel 2 may include an associated photosensitiveregion such as photodiode PD2. A microlens may be formed overphotodiodes PD1 and PD2 and may be used to direct incident light towardsphotodiodes PD1 and PD2. The arrangement of FIG. 2A in which microlens102 covers two pixel regions may sometimes be referred to as a 2×1 or1×2 arrangement because there are two phase detection pixels arrangedconsecutively in a line. In an alternate embodiment, three phasedetection pixels may be arranged consecutively in a line in what maysometimes be referred to as a 1×3 or 3×1 arrangement. In otherembodiments, phase detection pixels may be grouped in a 2×2 or 2×4arrangement. In general, phase detection pixels may be arranged in anydesired manner.

Color filters such as color filter elements 104 may be interposedbetween microlens 102 and substrate 108. Color filter elements 104 mayfilter incident light by only allowing predetermined wavelengths to passthrough color filter elements 104 (e.g., color filter 104 may only betransparent to the wavelengths corresponding to a green color, a redcolor, a blue color, a yellow color, a cyan color, a magenta color,visible light, infrared light, etc.). Color filter 104 may be abroadband color filter. Examples of broadband color filters includeyellow color filters (e.g., yellow color filter material that passes redand green light) and clear color filters (e.g., transparent materialthat passes red, blue, and green light). In general, broadband filterelements may pass two or more colors of light. Photodiodes PD1 and PD2may serve to absorb incident light focused by microlens 102 and producepixel signals that correspond to the amount of incident light absorbed.

Photodiodes PD1 and PD2 may each cover approximately half of thesubstrate area under microlens 102 (as an example). By only coveringhalf of the substrate area, each photosensitive region may be providedwith an asymmetric angular response (e.g., photodiode PD1 may producedifferent image signals based on the angle at which incident lightreaches pixel pair 100). The angle at which incident light reaches pixelpair 100 relative to a normal axis 116 (i.e., the angle at whichincident light strikes microlens 102 relative to the optical axis 116 oflens 102) may be herein referred to as the incident angle or angle ofincidence.

An image sensor can be formed using front side illumination imagerarrangements (e.g., when circuitry such as metal interconnect circuitryis interposed between the microlens and photosensitive regions) orbackside illumination imager arrangements (e.g., when photosensitiveregions are interposed between the microlens and the metal interconnectcircuitry). The example of FIGS. 2A, 2B, and 2C in which pixels 1 and 2are backside illuminated image sensor pixels is merely illustrative. Ifdesired, pixels 1 and 2 may be front side illuminated image sensorpixels. Arrangements in which pixels are backside illuminated imagesensor pixels are sometimes described herein as an example.

In the example of FIG. 2B, incident light 113 may originate from theleft of normal axis 116 and may reach pixel pair 100 with an angle 114relative to normal axis 116. Angle 114 may be a negative angle ofincident light. Incident light 113 that reaches microlens 102 at anegative angle such as angle 114 may be focused towards photodiode PD2.In this scenario, photodiode PD2 may produce relatively high imagesignals, whereas photodiode PD1 may produce relatively low image signals(e.g., because incident light 113 is not focused towards photodiodePD1).

In the example of FIG. 2C, incident light 113 may originate from theright of normal axis 116 and reach pixel pair 100 with an angle 118relative to normal axis 116. Angle 118 may be a positive angle ofincident light. Incident light that reaches microlens 102 at a positiveangle such as angle 118 may be focused towards photodiode PD1 (e.g., thelight is not focused towards photodiode PD2). In this scenario,photodiode PD2 may produce an image signal output that is relativelylow, whereas photodiode PD1 may produce an image signal output that isrelatively high.

The positions of photodiodes PD1 and PD2 may sometimes be referred to asasymmetric or displaced positions because the center of eachphotosensitive area 110 is offset from (i.e., not aligned with) opticalaxis 116 of microlens 102. Due to the asymmetric formation of individualphotodiodes PD1 and PD2 in substrate 108, each photosensitive area 110may have an asymmetric angular response (e.g., the signal outputproduced by each photodiode 110 in response to incident light with agiven intensity may vary based on an angle of incidence). It should benoted that the example of FIGS. 2A-2C where the photodiodes are adjacentis merely illustrative. If desired, the photodiodes may not be adjacent(i.e., the photodiodes may be separated by one or more interveningphotodiodes). In the diagram of FIG. 3, an example of the image signaloutputs of photodiodes PD1 and PD2 of pixel pair 100 in response tovarying angles of incident light is shown.

Line 160 may represent the output image signal for photodiode PD2whereas line 162 may represent the output image signal for photodiodePD1. For negative angles of incidence, the output image signal forphotodiode PD2 may increase (e.g., because incident light is focusedonto photodiode PD2) and the output image signal for photodiode PD1 maydecrease (e.g., because incident light is focused away from photodiodePD1). For positive angles of incidence, the output image signal forphotodiode PD2 may be relatively small and the output image signal forphotodiode PD1 may be relatively large.

The size and location of photodiodes PD1 and PD2 of pixel pair 100 ofFIGS. 2A, 2B, and 2C are merely illustrative. If desired, the edges ofphotodiodes PD1 and PD2 may be located at the center of pixel pair 100or may be shifted slightly away from the center of pixel pair 100 in anydirection. If desired, photodiodes 110 may be decreased in size to coverless than half of the pixel area.

Output signals from pixel pairs such as pixel pair 100 may be used toadjust the optics (e.g., one or more lenses such as lenses 28 of FIG. 1)in image sensor 14 during automatic focusing operations. The directionand magnitude of lens movement needed to bring an object of interestinto focus may be determined based on the output signals from pixelpairs 100.

For example, by creating pairs of pixels that are sensitive to lightfrom one side of the lens or the other, a phase difference can bedetermined. This phase difference may be used to determine both how farand in which direction the image sensor optics should be adjusted tobring the object of interest into focus.

When an object is in focus, light from both sides of the image sensoroptics converges to create a focused image. When an object is out offocus, the images projected by two sides of the optics do not overlapbecause they are out of phase with one another. By creating pairs ofpixels where each pixel is sensitive to light from one side of the lensor the other, a phase difference can be determined. This phasedifference can be used to determine the direction and magnitude ofoptics movement needed to bring the images into phase and thereby focusthe object of interest. Pixel blocks that are used to determine phasedifference information such as pixel pair 100 are sometimes referred toherein as phase detection pixels or depth-sensing pixels.

A phase difference signal may be calculated by comparing the outputpixel signal of PD1 with that of PD2. For example, a phase differencesignal for pixel pair 100 may be determined by subtracting the pixelsignal output of PD1 from the pixel signal output of PD2 (e.g., bysubtracting line 162 from line 160). For an object at a distance that isless than the focused object distance, the phase difference signal maybe negative. For an object at a distance that is greater than thefocused object distance, the phase difference signal may be positive.This information may be used to automatically adjust the image sensoroptics to bring the object of interest into focus (e.g., by bringing thepixel signals into phase with one another).

As previously mentioned, the example in FIGS. 2A-2C where phasedetection pixel block 100 includes two adjacent pixels is merelyillustrative. In another illustrative embodiment, phase detection pixelblock 100 may include multiple adjacent pixels that are covered byvarying types of microlenses.

FIG. 4 is a top view of an illustrative pixel that may be included in animage sensor such as image sensor 14. As shown, pixel 200 has at leasttwo different light collecting areas (LCAs). Pixel 200 may includephotodiodes with associated pixel circuitry used to capture the samespectrum of light. As an example, the pixels 200 may be used to capturered, green, blue, cyan, magenta, yellow, near-infrared, infrared, or anyother spectrum of light. A single red, green, blue, cyan, magenta,yellow, near-infrared, infrared, or clear color filter may be formedover the pixel 200. In certain embodiments, the color filter formed overpixel 200 may have areas that pass colored light and areas that areclear (i.e., that pass visible or full-spectrum light outside thevisible spectrum).

Pixel 200 of FIG. 4 may include a first sub-pixel 202, which may bereferred to as the inner sub-pixel 202. Inner sub-pixel 202 may becompletely surrounded by a second sub-pixel 204, which may be referredto as the outer sub-pixel 204. Inner sub-pixel 202 and outer sub-pixel204 may correspond to n-type doped photodiode regions in a semiconductorsubstrate. There may be respective sub-pixel circuitry in the substratesuch as transfer gates, floating diffusion regions, and reset gates ofthe pixel 200 that is coupled to the photodiode regions in thesub-pixels 202 and 204. The semiconductor substrate (not shown) may be abulk p-type substrate made of silicon, or any other suitablesemiconductor material.

A photodiode in inner sub-pixel 202 may have a circular shape at thesurface. In other words, the light collecting area of inner sub-pixel202 is a circular region. At the surface, the inner sub-pixel 202 mayhave a diameter S1. As an example, the diameter S1 of a photodiode ininner sub-pixel 202 may be 1 micron, but may alternatively be any otherdimension without departing from the scope of the present embodiment.Outer sub-pixel 204 may have a square outer boundary and a circularinner boundary at the surface. The area enclosed by the square outerboundary and circular inner boundary of outer sub-pixel 204 shown inFIG. 4 may correspond to the light collecting area of outer sub-pixel204. As shown in FIG. 4, the length of one of the sides of outersub-pixel 204 is S2. As an example, S2 may be 3 microns, but mayalternatively be any other dimension without departing from the scope ofthe present embodiment. The length S2 is preferably greater than thelength S1. Outer sub-pixel 204 is illustrated in FIG. 4 as having asquare outer boundary but may alternatively have a rectangular outerboundary.

If desired an optional isolation region may be formed between innersub-pixel 202 and outer sub-pixel 204. The isolation region may separateindividual sub-pixels in a given pixel from one another, and may alsoseparate individual sub-pixels in different respective pixels from oneanother. The optional isolation region may be formed from differenttypes of isolation devices such as trench isolation structures, dopedsemiconductor regions, metallic barrier structures, or any othersuitable isolation device.

Because inner sub-pixel 202 is surrounded by outer sub-pixel 204, innersub-pixel 202 may sometimes be described as being nested within outersub-pixel 204. Pixel 200 may sometimes be referred to as a nested imagepixel. The inner sub-pixel group and the outer sub-pixel group in anested image pixel may have the same geometric optical centers. In otherwords, because the outer sub-pixel group surrounds the inner sub-pixelgroup symmetrically, the center of the surface of the inner sub-pixelgroup is the same as the center of the outer sub-pixel group thatsurrounds the inner sub-pixel group.

The inner sub-pixel 202 may have a lower sensitivity to incident light,and may be referred to as having a lower sensitivity light collectingarea compared to outer sub-pixel 204. The respective dopingconcentrations of inner sub-pixel 202 and outer sub-pixel 204 may bedifferent or they may be the same. As an example, the dopingconcentrations of photodiode regions in inner sub-pixel 202 may bemodified to reduce the sensitivity of inner sub-pixel 202 to light.However, for the sake of simplicity in explaining and highlighting theproperties of the pixel 200, it will be assumed that the sub-pixels 202and 204 have photodiodes with the same doping concentrations. The lowersensitivity to incident light of inner sub-pixel 202 compared to outersub-pixel 204 may be a result of the lower light collecting area ofinner sub-pixel 202 compared to the light collecting area of outersub-pixel 204.

The ratio of the light sensitivity of the outer sub-pixel group to thelight sensitivity of the inner sub-pixel group may be at least 4 to 1,but could be 5 to 1, 10 to 1, any intermediate ratio, or any largerratio. In other words, the light sensitivity of the outer sub-pixelgroup may be at least four times greater than the light sensitivity ofthe inner sub-pixel group.

One or more microlenses may be formed over the pixel 200 of FIG. 4 todirect light toward the outer sub-pixel 204. The one or more microlensesmay be formed over the color filter formed over pixel 200. To directlight toward outer sub-pixel 204, the one or more microlenses may beformed over only outer sub-pixel 204. As shown in FIG. 4, microlens 206is a toroidal microlens that covers outer sub-pixel 204. The toroidalmicrolens has an opening that overlaps inner sub-pixel 202 such that themicrolens does not overlap inner sub-pixel 202. This enables light to bedirected towards the outer sub-pixel. In some embodiments however, theone or more microlenses that direct light toward outer sub-pixel 204 maypartially or completely overlap the light collecting area of sub-pixel202. Directing light toward outer sub-pixel 204 may further increase thesensitivity of the light collecting area of outer sub-pixel 204 relativeto the sensitivity of the light collecting area of inner sub-pixel 202.In some embodiments, inner sub-pixel 202 may optionally be covered by amicrolens that is formed separately from microlens 206.

Because a larger amount of light incident on pixel 200 is directed toouter sub-pixel 204 than to inner sub-pixel 202, inner sub-pixel 202 issaid to have a lower sensitivity light collecting area compared to outersub-pixel 204. The difference in sensitivity to light of inner sub-pixel202 and outer sub-pixel 204 enables pixel 200 to be used in high dynamicrange applications while using the same integration time for eachsub-pixel. If desired, the integration time for each sub-pixel may bedifferent to further increase the dynamic range of the pixel.

It may be desirable to provide phase detection capabilities in a pixelof the type shown in FIG. 4. FIG. 5 shows an illustrative imaging pixelwith high dynamic range functionality and phase detection capability. Asshown in FIG. 5, pixel 200 may include an inner sub-pixel 202.Additionally, pixel 200 may include two outer sub-pixels 204-1 and204-2. Sub-pixels 204-1 and 204-2 may sometimes collectively be referredto as outer sub-pixel group 204. By splitting the outer sub-pixel group204 into two separate outer sub-pixels, the outer sub-pixel group mayhave phase detection capabilities (e.g., sub-pixels 204-1 and 204-2 mayeach have an asymmetric response to incident light). In FIGS. 4 and 5,toroidal microlens 206 is shown as not overlapping inner sub-pixel 202.This example is merely illustrative. If desired, toroidal microlens 206may partially overlap inner sub-pixel 202. The microlens may divertlight away from inner sub-pixel 202 towards outer sub-pixel group 204.

FIG. 6 shows a cross-sectional bottom view of the front side of anillustrative imaging pixel with an outer sub-pixel group containing twosub-pixels. FIG. 7 shows a cross-sectional top view of the backside ofthe imaging pixel shown in FIG. 6. As shown in FIG. 6, at the front sideof the pixel (i.e., the side on which the pixel's processing circuitryis formed) first and second outer sub-pixels 204-1 and 204-2 may have arectangular shape. Inner sub-pixel 202 may be formed between outersub-pixels 204-1 and 204-2. Additionally, a floating diffusion region208 may be formed between outer sub-pixels 204-1 and 204-2. Floatingdiffusion region 208 may be configured to receive charge transferredfrom one or more of inner sub-pixel 202, outer sub-pixel 204-1, andouter sub-pixel 204-2. As shown in FIG. 7, at the backside of the pixel(i.e., the side that is exposed to incident light) the outer sub-pixelsmay have outer sub-pixel extensions. Outer sub-pixel 204-1 may haveouter sub-pixel extensions 204-1′, while outer sub-pixel 204-2 may haveouter sub-pixel extensions 204-2′. The outer sub-pixel extensions mayhelp maximize the light collecting area at the backside of the imagingpixel. The outer sub-pixel extensions 204-1′ may be separated from outersub-pixel extensions 204-2′ by a distance 210. This distance may be anydesired distance (e.g., less than 1 micron, less than 0.1 micron, lessthan 0.01 micron, greater than 0.01 micron, greater than 0.1 micron,etc.).

In FIGS. 4 and 5, a microlens arrangement was shown where a singletoroidal microlens covers pixel 200. This example is merelyillustrative, and any desired microlens arrangement may be used to coverpixel 200. For example, FIG. 8 shows an embodiment where a singlecircular microlens covers pixel 200. Microlens 206 may cover both innersub-pixel 202 and outer sub-pixel group 204. Microlens 206 in FIG. 8 maynot have any openings (as opposed to the microlens in FIGS. 4 and 5).Microlens 206 in FIG. 8 may sometimes be referred to as a monocularmicrolens.

In another illustrative embodiment shown in FIG. 9, pixel 200 may becovered by four circular microlenses. Microlenses 206-1 and 206-2 maycover portions of outer sub-pixel 204-1. Microlenses 206-3 and 206-4 maycover portions of outer sub-pixel 204-2. In FIG. 9, microlenses 206-1,206-2, 206-3, and 206-4 are shown as not overlapping inner sub-pixel202. This example is merely illustrative. If desired, microlenses 206-1,206-2, 206-3, and 206-4 may partially overlap inner sub-pixel 202. Themicrolenses may divert light away from inner sub-pixel 202 towards outersub-pixels 204-1 and 204-2.

In yet another illustrative embodiment, pixel 200 may be covered by twoelliptical microlenses. An arrangement of this type is shown in FIG. 10.As shown in FIG. 10, a first elliptical microlens 206-1 may coverportions of both outer sub-pixel 204-1 and outer sub-pixel 204-2. Asecond elliptical microlens 206-2 may also cover portions of outersub-pixel 204-1 and outer sub-pixel 204-2. In FIG. 10, microlenses 206-1and 206-2 are shown as partially overlapping inner sub-pixel 202. Thisexample is merely illustrative. If desired, microlenses 206-1 and 206-2may not overlap inner sub-pixel 202.

In FIGS. 5-10, outer sub-pixel group 204 is shown as being split suchthat sub-pixels 204-1 and 204-2 are horizontally oriented (i.e., theouter sub-pixel group is split with a vertical divide such thatsub-pixels 204-1 and 204-2 are horizontally adjacent). The horizontalorientation of sub-pixels 204-1 and 204-2 may enable the pixel to detectvertical edges in a scene. The example of outer sub-pixel group 204being split so that sub-pixels 204-1 and 204-2 are horizontally adjacentis merely illustrative. If desired, outer sub-pixel group 204 may besplit so that sub-pixels 204-1 and 204-2 are vertically adjacent. Anarrangement of this type is shown in FIG. 11. As shown, pixel 200 mayhave an inner sub-pixel 202 similar to those shown in FIGS. 5-10. Pixel200 may also have an outer sub-pixel group 204. However, in FIG. 11 theouter sub-pixel group may be split such that outer sub-pixel 204-1 isvertically adjacent to outer sub-pixel 204-2. The vertical orientationof sub-pixels 204-1 and 204-2 in FIG. 11 may enable the pixel to detecthorizontal edges in a scene.

In yet another embodiment, outer sub-pixel group 204 may be splitdiagonally, as shown in FIG. 12. Splitting outer sub-pixel group 204diagonally may result in sub-pixels 204-1 and 204-2 as shown in FIG. 12.Pixel 200 in FIG. 12 may be suited to detecting diagonal edges in ascene. In general, outer sub-pixel group 204 may be split in any desiredmanner.

In FIGS. 4-12, inner sub-pixel 202 is shown as being a single lightcollecting area. However, it may be desirable to provide the innersub-pixel with phase detection capabilities. FIG. 13 shows anillustrative imaging pixel with high dynamic range functionality andphase detection capability. As shown in FIG. 13, pixel 200 may includean outer sub-pixel 204. Outer sub-pixel 204 may enclose an innersub-pixel group 202. Inner sub-pixel group 202 may be split into innersub-pixel 202-1 and inner sub-pixel 202-2. By splitting the innersub-pixel group 202 into two separate inner sub-pixels, the innersub-pixel group may have phase detection capabilities. Inner sub-pixelgroup 202 may be split to form horizontally adjacent inner sub-pixels(as shown in FIG. 13) or may be split to form vertically adjacent innersub-pixels. Inner sub-pixel group 202 may also be split diagonally. FIG.13 shows a toroidal microlens that covers outer sub-pixel 204 withoutcovering inner sub-pixel 202. This example is merely illustrative, andother microlens arrangements may be used if desired. For example, ifdesired pixel 200 may include a toroidal microlens that covers outersub-pixel group 204 and a circular microlens that covers inner sub-pixelgroup 202. In another illustrative embodiment, a single circularmicrolens may cover both outer sub-pixel group 204 and inner sub-pixelgroup 202.

In certain embodiments, both inner sub-pixel group 202 and outersub-pixel group 204 may be split to provide phase detectioncapabilities. An arrangement of this type is shown in FIG. 14. As shown,outer sub-pixel group 204 is split such that outer sub-pixel 204-1 andouter sub-pixel 204-2 are horizontally adjacent. Similarly, innersub-pixel group 202 is split such that inner sub-pixel 202-1 and innersub-pixel 202-2 are horizontally adjacent. Pixel 200 will therefore beable to obtain phase detection data from sub-pixels 202-1 and 202-2 aswell as sub-pixels 204-1 and 204-2.

The example of FIG. 14 where inner sub-pixel group 202 and outersub-pixel group 204 are both split in the same orientation is merelyillustrative. If desired, inner sub-pixel group 202 and outer sub-pixelgroup 204 may be split in separate orientations to provide phasedetection data for multiple directions. As shown in FIG. 15, outersub-pixel group 204 is split such that outer sub-pixel 204-1 and outersub-pixel 204-2 are horizontally adjacent. However, inner sub-pixelgroup 202 is split such that inner sub-pixel 202-1 and inner sub-pixel202-2 are vertically adjacent. This enables the pixel of FIG. 15 todetect both vertical and horizontal edges (while the pixel of FIG. 14may be used to detect only vertical edges).

Instead of splitting inner sub-pixel group 202 into two separatesub-pixels to enable phase detection capabilities, a portion of innersub-pixel group 202 may instead be covered by a shielding layer. Asshown in FIG. 16, half of inner sub-pixel 202 may be covered byshielding layer 212. Shielding layer 212 may formed from metal oranother material that is opaque to incident light. The uncovered portionof inner sub-pixel 202 will have an asymmetric angular response toincident light, enabling pixel 200 of FIG. 16 to be used in phasedetection applications.

It should be understood that the previous examples of pixels shown inFIGS. 4-16 are merely illustrative, and that the concepts shown can becombined in any desired combination. For example, a number of microlensarrangements have been described (e.g., a single circular microlens, asingle toroidal microlens, two elliptical microlenses, four circularmicrolenses, etc.). A number of arrangements for an outer sub-pixelgroup have been described (e.g., a single outer sub-pixel, an outersub-pixel group that is split horizontally, an outer sub-pixel groupthat is split vertically, an outer sub-pixel group that is splitdiagonally, etc.). A number of arrangements for an inner sub-pixel grouphave been described (e.g., a single inner sub-pixel, an inner sub-pixelgroup that is split horizontally, an inner sub-pixel group that is splitvertically, an inner sub-pixel group that is split diagonally, an innersub-pixel that is partially covered by a shielding layer, etc.). Anydesired microlens arrangement, inner sub-pixel arrangement, and outersub-pixel arrangement may be used depending on the specific designconsiderations of the pixel.

Pixels such as those shown FIGS. 4-16 may be arranged in a pixel arrayin image sensor 14. Each pixel may have a corresponding color filterelement that covers the inner sub-pixels and outer sub-pixels for thatpixel. The color filter elements may be part of a color filter array.The pattern of color filters in the pixel array may be a Bayer mosaicpattern which includes a repeating unit cell of two-by-two pixels havingtwo green image pixels arranged on one diagonal and one red and one blueimage pixel arranged on the other diagonal. This example is merelyillustrative, and other color filter patterns may be used if desired.For example, a broadband color filter (e.g., a yellow or clear colorfilter) may be used instead of a green color filter in the color filterarray.

A number of other color filter patterns may be used if desired. Forexample, a monochrome pattern may be used. A color filter pattern withinfrared or near-infrared filter elements may be used. In yet anotherillustrative embodiment, a color filter pattern with red and clear colorfilter elements (e.g., RCCC) or a color filter pattern with red, green,and clear color filter elements (e.g., RCCG) may be used. Additionally,the aforementioned example of the color filter pattern having arepeating unit cell of two-by-two pixels is merely illustrative. Thecolor filter pattern may have a repeating unit cell of any desired sizeor shape (e.g., three-by-three, four-by-four, two-by-four, etc.).

Just as the color filter pattern includes a unit cell of two-by-twopixels that is repeated across the pixel array, the structure of thepixels may match the pattern of a unit cell that is repeated across thearray. In other words, different pixels in the pixel array may havedifferent structure. This may help optimize the dynamic range and phasedetection performance of the image sensor.

An exemplary pattern of pixels is shown in FIG. 17. Pixels marked withan R include a red color filter, pixels marked with a G include a greencolor filter, and pixels marked with a B include a blue color filter.FIG. 17 (and subsequent FIGS. 18-24) show a Bayer color filter pattern.However, any desired color filter pattern may be used in the pixelarray. As shown in FIG. 17, repeating unit cell 214-1 may include fourpixels in a two-by-two arrangement. Pixels 200-1, 200-2, 200-3, and200-4 may be included in repeating unit cell 214-1. Each pixel inrepeating unit cell 214-1 may include two separate sub-pixels 204-1 and204-2. The sub-pixels may enable the image sensor to gather phasedetection data. The orientation of the sub-pixels may be varied indifferent pixels in the unit cell. As shown in FIG. 17, pixels 200-1 and200-4 (the upper left and lower right pixels, respectively) may both behorizontally oriented while pixels 200-2 and 200-3 (the upper right andlower left pixels, respectively), may both be vertically oriented. Byvarying the orientation of pixels within the unit cell, the unit cell isable to gather multiple directions of phase detection data. Unit cell214-1 may be repeated across the entire pixel array. As shown, theadjacent 2×2 group of pixels 214-2 is identical to the unit cell 214-1.

FIG. 18 shows another exemplary pattern of pixels. As shown in FIG. 18,repeating unit cell 214-1 may include four pixels in a two-by-twoarrangement. Pixels 200-1, 200-2, 200-3, and 200-4 may be included inrepeating unit cell 214-1. Each pixel in repeating unit cell 214-1 mayinclude two separate sub-pixels 204-1 and 204-2. The sub-pixels mayenable the image sensor to gather phase detection data. The orientationof the sub-pixels may be varied in different pixels in the unit cell. Asshown in FIG. 18, pixels 200-1 and 200-2 (the upper left and upper rightpixels, respectively) may both be horizontally oriented while pixels200-3 and 200-4 (the lower left and lower right pixels, respectively)may both be vertically oriented. By varying the orientation of pixelswithin the unit cell, the unit cell is able to gather multipledirections of phase detection data. The unit cell 214-2 adjacent to unitcell 214-1 may be identical to unit cell 214-1 except the orientation ofthe sub-pixels may be reversed. In other words, pixels that arehorizontally oriented in unit cell 214-1 are vertically oriented in unitcell 214-2 and pixels that are vertically oriented in unit cell 214-1are horizontally oriented in unit cell 214-2. For example, horizontallyoriented pixel 200-1 in unit cell 214-1 becomes vertically orientedpixel 200-5 in unit cell 214-2, while vertically oriented pixel 200-3 inunit cell 214-1 becomes horizontally oriented pixel 200-7 in unit cell214-2. Unit cells 214-1 and 214-2 may collectively be referred to as a2×4 unit cell 214. The 2×4 unit cell 214 may be repeated across theentire pixel array.

Unit cell 214-2 may be described as having pixels with orientations thatare the opposite of the orientation of the pixels in unit cell 214-1.Said another way, the pixels of unit cell 214-2 may be the same as thepixels of unit cell 214-1 except rotated 90 degrees.

Using the 2×4 unit cell 214 shown in FIG. 18 may have the advantage ofbeing able to detect vertical and horizontal edges in each colorchannel. For example, the data from the unit cell of FIG. 18 enablesdetection of horizontal and vertical green edges, horizontal andvertical blue edges, and horizontal and vertical red edges. Incomparison, the arrangement of FIG. 17 may only enable detection ofvertical green edges, horizontal blue edges, and horizontal red edges.

FIGS. 17 and 18 show each pixel having a single circular microlens 206.However, this example is merely illustrative and each pixel may have anydesired microlens arrangement. Each pixel in the pixel array may havethe same microlens arrangement (as shown in FIGS. 17 and 18) ordifferent pixels in the pixel array may have different microlensarrangements.

FIG. 19 shows another exemplary pattern of pixels where each pixel hasan outer sub-pixel group and an inner sub-pixel group. As shown in FIG.19, repeating unit cell 214-1 may include four pixels in a two-by-twoarrangement. Pixels 200-1, 200-2, 200-3, and 200-4 may be included inrepeating unit cell 214-1. Each pixel in repeating unit cell 214-1 mayinclude outer sub-pixels 204-1 and 204-2 that surround inner sub-pixel202. The sub-pixels may enable the image sensor to gather phasedetection data and have a high dynamic range. The orientation of thesub-pixels may be varied in different pixels in the unit cell. As shownin FIG. 19, pixels 200-1 and 200-4 (the upper left and lower rightpixels, respectively) may both be horizontally oriented while pixels200-2 and 200-3 (the upper right and lower left pixels, respectively)may both be vertically oriented. By varying the orientation of pixelswithin the unit cell, the unit cell is able to gather multipledirections of phase detection data. Unit cell 214-1 may be repeatedacross the entire pixel array. As shown, the adjacent 2×2 group ofpixels 214-2 is identical to the unit cell 214-1.

FIG. 20 shows an exemplary pattern of pixels similar to the patternshown in FIG. 19. Unit cell 214-1 in FIG. 20 may be identical to unitcell 214-1 in FIG. 19. However, the orientation of the sub-pixels inunit cell 214-2 in FIG. 20 may be reversed when compared to unit cell214-1 in FIG. 20 (similar to the change in orientation between unitcells 214-1 and 214-2 described in connection with FIG. 18). Unit cells214-1 and 214-2 in FIG. 20 may collectively be referred to as a 2×4 unitcell 214. The 2×4 unit cell 214 in FIG. 20 may be repeated across theentire pixel array.

FIG. 21 shows another exemplary pattern of pixels where each pixel hasan outer sub-pixel group and an inner sub-pixel group. As shown in FIG.21, repeating unit cell 214-1 may include four pixels in a two-by-twoarrangement. Pixels 200-1, 200-2, 200-3, and 200-4 may be included inrepeating unit cell 214-1. Each pixel in repeating unit cell 214-1 mayinclude outer sub-pixels 204-1 and 204-2 that surround inner sub-pixelgroup 202. Each inner sub-pixel group 202 may include inner sub-pixels202-1 and 202-2. The sub-pixels may enable the image sensor to gatherphase detection data for both the inner and outer sub-pixels and have ahigh dynamic range. The orientation of the sub-pixels may be varied indifferent pixels in the unit cell. As shown in FIG. 21, pixels 200-1 and200-2 (the upper left and upper right pixels, respectively) may bothhave horizontally oriented outer sub-pixels and horizontally orientedinner sub-pixels while pixels 200-3 and 200-4 (the lower left and lowerright pixels, respectively) may both have vertically oriented outersub-pixels and vertically oriented inner sub-pixels. By varying theorientation of pixels within the unit cell, the unit cell is able togather multiple directions of phase detection data. Unit cell 214-1 maybe repeated across the entire pixel array. As shown, the adjacent 2×2group of pixels 214-2 is identical to the unit cell 214-1.

The example provided in FIG. 21 where the orientation of the innersub-pixels matches the orientation of the outer sub-pixels is merelyillustrative. If desired, pixels may be used in the repeating unit cellwhere the orientation of the inner sub-pixels is different from theorientation of the outer sub-pixels (as discussed in connection withFIG. 15).

FIG. 22 shows yet another exemplary pattern of pixels where each pixelhas an outer sub-pixel group and an inner sub-pixel group. As shown inFIG. 22, repeating unit cell 214 may include eight pixels in atwo-by-four arrangement. Pixels 200-1, 200-2, 200-3, 200-4, 200-5,200-6, 200-7, and 200-8 may be included in repeating unit cell 214. Eachpixel in repeating unit cell 214 may include outer sub-pixels 204-1 and204-2 that surround inner sub-pixel group 202. Each pixel's outersub-pixels may gather phase detection information. The orientation ofthe outer sub-pixels may be varied in different pixels in the unit cell.As shown in FIG. 22, pixels 200-1, 200-2, 200-5, and 200-6 may havehorizontally oriented outer sub-pixels while pixels 200-3, 200-4, 200-7,and 200-8 may have vertically oriented outer sub-pixels. By varying theorientation of the outer sub-pixels within the unit cell, the unit cellis able to gather multiple directions of phase detection data.

Additionally, repeating unit cell 214 may be provided with shieldinglayers to enable additional phase detection. The inner sub-pixels forpixels 200-2, 200-3, 200-4, 200-6, 200-7, and 200-8 may have symmetricangular responses to incident light and therefore may not be used togather phase detection data. However, pixels 200-1 and 200-5 may beprovided with shielding layers to cause inner sub-pixel 202 to have anasymmetric angular response to incident light (as discussed inconnection with FIG. 16). As shown, shielding layer 212-1 may cover theleft half of inner sub-pixel 202 in pixel 200-1, while shielding layer212-2 may cover the right half of inner sub-pixel 202 in pixel 200-5.The data from the uncovered portions of inner sub-pixels 202 in pixels200-1 and 200-5 may be used together to determine phase information.

FIG. 23 shows another exemplary pattern of pixels where each pixel hasan outer sub-pixel group and an inner sub-pixel and shielding layerspartially covering the inner sub-pixels. As shown in FIG. 23, repeatingunit cell 214-1 may include four pixels in a two-by-two arrangement.Pixels 200-1, 200-2, 200-3, and 200-4 may be included in repeating unitcell 214. Each pixel in repeating unit cell 214-1 may include outersub-pixels 204-1 and 204-2 that surround inner sub-pixel group 202. Eachpixel's outer sub-pixels may gather phase detection information. Theorientation of the outer sub-pixels may be varied in different pixels inthe unit cell. As shown in FIG. 23, pixels 200-1 and 200-2 may havehorizontally oriented outer sub-pixels while pixels 200-3 and 200-4 mayhave vertically oriented outer sub-pixels. By varying the orientation ofthe outer sub-pixels within the unit cell, the unit cell is able togather multiple directions of phase detection data.

Additionally, repeating unit cell 214 may be provided with shieldinglayers to enable additional phase detection. The inner sub-pixels forpixels 200-2 and 200-3 may have symmetric angular responses to incidentlight and therefore may not be used to gather phase detection data.However, pixels 200-1 and 200-4 may be provided with shielding layers tocause inner sub-pixel 202 to have an asymmetric angular response toincident light (as discussed in connection with FIG. 16). As shown,shielding layer 212-1 may cover the left half of inner sub-pixel 202 inpixel 200-1, while shielding layer 212-2 may cover the right half ofinner sub-pixel 202 in pixel 200-4. The data from the uncovered portionsof inner sub-pixels 202 in pixels 200-1 and 200-4 may be used togetherto determine phase information. Unit cell 214-1 may be repeated acrossthe entire pixel array. As shown, the adjacent 2×2 group of pixels 214-2is identical to the unit cell 214-1.

FIG. 24 shows yet another exemplary pattern of pixels where each pixelhas an outer sub-pixel group and an inner sub-pixel group. As shown inFIG. 24, repeating unit cell 214 may include eight pixels in atwo-by-four arrangement. Pixels 200-1, 200-2, 200-3, 200-4, 200-5,200-6, 200-7, and 200-8 may be included in repeating unit cell 214. Eachpixel in repeating unit cell 214 may include outer sub-pixels 204-1 and204-2 that surround inner sub-pixel group 202. Each pixel's outersub-pixels may gather phase detection information. The orientation ofthe outer sub-pixels may be varied in different pixels in the unit cell.As shown in FIG. 24, pixels 200-1, 200-2, 200-5, and 200-6 may havehorizontally oriented outer sub-pixels while pixels 200-3, 200-4, 200-7,and 200-8 may have vertically oriented outer sub-pixels. By varying theorientation of the outer sub-pixels within the unit cell, the unit cellis able to gather multiple directions of phase detection data.

Additionally, repeating unit cell 214 may be provided with shieldinglayers to enable additional phase detection. The inner sub-pixels forpixels 200-2, 200-3, 200-6, and 200-7 may have symmetric angularresponses to incident light and therefore may not be used to gatherphase detection data. However, pixels 200-1 and 200-5 may be providedwith shielding layers to cause inner sub-pixel 202 to have an asymmetricangular response to incident light (as discussed in connection with FIG.16). As shown, shielding layer 212-1 may cover the left half of innersub-pixel 202 in pixel 200-1, while shielding layer 212-2 may cover theright half of inner sub-pixel 202 in pixel 200-5. The data from theuncovered portions of inner sub-pixels 202 in pixels 200-1 and 200-5 maybe used together to determine phase information. In particular, the datafrom the uncovered portions of inner sub-pixels 202 in pixels 200-1 and200-5 may be used together to detect vertical edges in a scene.Additionally, pixels 200-4 and 200-8 may be provided with shieldinglayers to cause inner sub-pixel 202 to have an asymmetric angularresponse to incident light (as discussed in connection with FIG. 16). Asshown, shielding layer 212-3 may cover the bottom half of innersub-pixel 202 in pixel 200-4, while shielding layer 212-4 may cover thetop half of inner sub-pixel 202 in pixel 200-8. The data from theuncovered portions of inner sub-pixels 202 in pixels 200-4 and 200-8 maybe used together to determine phase information. In particular, the datafrom the uncovered portions of inner sub-pixels 202 in pixels 200-4 and200-8 may be used together to detect horizontal edges in a scene.

Using the arrangement of FIG. 24, the outer sub-pixel groups and innersub-pixel groups may both be able to detect vertical and horizontaledges. Additionally, because the inner sub-pixels are less sensitive tolight than the outer sub-pixels, the pattern shown in FIG. 24 may beused to produce high dynamic range images.

FIGS. 19-24 show each pixel having a single toroidal microlens 206.However, this example is merely illustrative and each pixel may have anydesired microlens arrangement. Each pixel in the pixel array may havethe same microlens arrangement (as shown in FIGS. 19-24) or differentpixels in the pixel array may have different microlens arrangements.

In various embodiments of the invention, an image pixel may include aninner sub-pixel group that exhibits a first light sensitivity and anouter sub-pixel group that includes at least one sub-pixel and thatexhibits a second light sensitivity that is greater than the first lightsensitivity. The inner sub-pixel group may include first and secondinner sub-pixels, and the first and second inner sub-pixels may eachhave an asymmetric angular response to incident light and may beconfigured to generate phase detection data. The inner sub-pixel groupmay be nested within the outer sub-pixel group.

The image pixel may also include a color filter formed over the innersub-pixel group and the outer sub-pixel group. The second lightsensitivity may be at least four times greater than the first lightsensitivity. The outer sub-pixel group may have a first geometriccenter, and the inner sub-pixel group may have a second geometric centerthat is the same as the first geometric center. The outer sub-pixelgroup may include first and second outer sub-pixels, and the first andsecond outer sub-pixels may each have an asymmetric angular response toincident light and may be configured to generate phase detection data.The first and second outer sub-pixels may be horizontally adjacent, andthe first and second inner sub-pixels may be horizontally adjacent. Thefirst and second outer sub-pixels may be horizontally adjacent, and thefirst and second inner sub-pixels may be vertically adjacent.

In various embodiments a pixel array may include a plurality of pixels.Each pixel of the plurality of pixels may have a structure that followsa pattern, the pattern may include a repeating unit cell of two-by-twopixels that is repeated across the entire pixel array, and the repeatingunit cell of two-by-two pixels may include first, second, third, andfourth pixels. Each pixel may include an inner sub-pixel group that isnested within an outer sub-pixel group, each outer sub-pixel group mayinclude first and second outer sub-pixels that are configured togenerate phase detection data, the first and second outer sub-pixels ofthe first pixel may be horizontally adjacent, and the first and secondouter sub-pixels of the second pixel may be vertically adjacent.

The first pixel may be an upper left pixel of the repeating unit cell oftwo-by-two pixels, the second pixel may be an upper right pixel of therepeating unit cell of two-by-two pixels, the third pixel may be a lowerleft pixel of the repeating unit cell of two-by-two pixels, the fourthpixel may be a lower right pixel of the repeating unit cell oftwo-by-two pixels, the first and second outer sub-pixels of the thirdpixel may be vertically adjacent, and the first and second outersub-pixels of the fourth pixel may be horizontally adjacent. The firstpixel may be covered by a green color filter element, the second pixelmay be covered by a red color filter element, the third pixel may becovered by a blue color filter element, and the fourth pixel may becovered by a green color filter element.

The first pixel may be an upper left pixel of the repeating unit cell oftwo-by-two pixels, the second pixel may be a lower left pixel of therepeating unit cell of two-by-two pixels, the third pixel may be anupper right pixel of the repeating unit cell of two-by-two pixels, thefourth pixel may be a lower right pixel of the repeating unit cell oftwo-by-two pixels, the first and second outer sub-pixels of the thirdpixel may be horizontally adjacent, and the first and second outersub-pixels of the fourth pixel may be vertically adjacent. The firstpixel may be covered by a green color filter element, the second pixelmay be covered by a blue color filter element, the third pixel may becovered by a red color filter element, and the fourth pixel may becovered by a green color filter element.

Each inner sub-pixel group may include first and second inner sub-pixelsthat are configured to generate phase detection data. The first andsecond inner sub-pixels of the first pixel may be horizontally adjacent,and the first and second inner sub-pixels of the second pixel may bevertically adjacent. The first and second inner sub-pixels of the firstpixel may be vertically adjacent. The repeating unit cell of two-by-twopixels may also include a first shielding layer that covers a left halfof the inner sub-pixel group of the third pixel and a second shieldinglayer that covers a right half of the inner sub-pixel group of thefourth pixel.

A pixel array may include a plurality of pixels. Each pixel of theplurality of pixels may have a structure that follows a pattern, thepattern may include a repeating unit cell of two-by-four pixels that isrepeated across the entire pixel array, and the repeating unit cell oftwo-by-four pixels may include a first two-by-two group of pixels and asecond two-by-two group of pixels that is adjacent to the firsttwo-by-two group of pixels. The first two-by-two group of pixels mayinclude an upper left pixel, an upper right pixel, a lower left pixel,and a lower right pixel that each have first and second sub-pixels thatare arranged in a respective orientation and are configured to generatephase detection data. The second two-by-two group of pixels may includean upper left pixel, an upper right pixel, a lower left pixel, and alower right pixel that each have first and second sub-pixels that arearranged in a respective orientation and are configured to generatephase detection data. The orientations of the pixels in the secondtwo-by-two group of pixels may be the opposite of the orientations ofthe pixels in the first two-by-two group of pixels.

The upper left pixel in the first two-by-two group of pixels may havefirst and second sub-pixels that are horizontally adjacent, the upperleft pixel in the second two-by-two group of pixels may have first andsecond sub-pixels that are vertically adjacent, the upper right pixel inthe first two-by-two group of pixels may have first and secondsub-pixels that are horizontally adjacent, the upper right pixel in thesecond two-by-two group of pixels may have first and second sub-pixelsthat are vertically adjacent, the lower left pixel in the firsttwo-by-two group of pixels may have first and second sub-pixels that arevertically adjacent, the lower left pixel in the second two-by-two groupof pixels may have first and second sub-pixels that are horizontallyadjacent, the lower right pixel in the first two-by-two group of pixelsmay have first and second sub-pixels that are vertically adjacent, andthe lower right pixel in the second two-by-two group of pixels may havefirst and second sub-pixels that are horizontally adjacent.

The upper left pixel in the first two-by-two group of pixels may havefirst and second sub-pixels that are horizontally adjacent, the upperleft pixel in the second two-by-two group of pixels may have first andsecond sub-pixels that are vertically adjacent, the upper right pixel inthe first two-by-two group of pixels may have first and secondsub-pixels that are vertically adjacent, the upper right pixel in thesecond two-by-two group of pixels may have first and second sub-pixelsthat are horizontally adjacent, the lower left pixel in the firsttwo-by-two group of pixels may have first and second sub-pixels that arevertically adjacent, the lower left pixel in the second two-by-two groupof pixels may have first and second sub-pixels that are horizontallyadjacent, the lower right pixel in the first two-by-two group of pixelsmay have first and second sub-pixels that are horizontally adjacent, andthe lower right pixel in the second two-by-two group of pixels may havefirst and second sub-pixels that are vertically adjacent.

The upper left pixel in the first two-by-two group of pixels and theupper left pixel in the second two-by-two group of pixels may both becovered by respective color filter elements of a first color, the upperright pixel in the first two-by-two group of pixels and the upper rightpixel in the second two-by-two group of pixels may both be covered byrespective color filter elements of a second color, the lower left pixelin the first two-by-two group of pixels and the lower left pixel in thesecond two-by-two group of pixels may both be covered by respectivecolor filter elements of a third color, and the lower right pixel in thefirst two-by-two group of pixels and the lower right pixel in the secondtwo-by-two group of pixels may both be covered by respective colorfilter elements of a fourth color.

The foregoing is merely illustrative of the principles of this inventionand various modifications can be made by those skilled in the artwithout departing from the scope and spirit of the invention.

What is claimed is:
 1. A pixel array comprising a plurality of pixels, wherein each pixel of the plurality of pixels has a structure that follows a pattern, wherein the pattern comprises a repeating unit cell of two-by-two pixels that is repeated across the pixel array, and wherein the repeating unit cell of two-by-two pixels comprises: first, second, third, and fourth pixels, wherein each pixel comprises an inner sub-pixel group that is nested within an outer sub-pixel group, wherein each outer sub-pixel group comprises first and second outer sub-pixels that are configured to generate phase detection data, wherein the first and second outer sub-pixels of the first pixel have a first orientation, and wherein the first and second outer sub-pixels of the second pixel have a second orientation that is different than the first orientation.
 2. The pixel array defined in claim 1, wherein the first pixel is an upper left pixel of the repeating unit cell of two-by-two pixels, wherein the second pixel is an upper right pixel of the repeating unit cell of two-by-two pixels, wherein the third pixel is a lower left pixel of the repeating unit cell of two-by-two pixels, wherein the fourth pixel is a lower right pixel of the repeating unit cell of two-by-two pixels, and wherein the first orientation is orthogonal to the second orientation.
 3. The pixel array defined in claim 2, wherein the first and second outer sub-pixels of the first pixel are horizontally adjacent and wherein the first and second outer sub-pixels of the second pixel are vertically adjacent.
 4. The pixel array defined in claim 3, wherein the first and second outer sub-pixels of the third pixel are vertically adjacent and wherein the first and second outer sub-pixels of the fourth pixel are horizontally adjacent.
 5. The pixel array defined in claim 2, wherein the first pixel is covered by a green color filter element, wherein the second pixel is covered by a red color filter element, wherein the third pixel is covered by a blue color filter element, and wherein the fourth pixel is covered by a green color filter element.
 6. The pixel array defined in claim 1, wherein the first pixel is an upper left pixel of the repeating unit cell of two-by-two pixels, wherein the second pixel is a lower left pixel of the repeating unit cell of two-by-two pixels, wherein the third pixel is an upper right pixel of the repeating unit cell of two-by-two pixels, wherein the fourth pixel is a lower right pixel of the repeating unit cell of two-by-two pixels, wherein the first and second outer sub-pixels of the first pixel are horizontally adjacent, wherein the first and second outer sub-pixels of the second pixel are vertically adjacent, wherein the first and second outer sub-pixels of the third pixel are horizontally adjacent, and wherein the first and second outer sub-pixels of the fourth pixel are vertically adjacent.
 7. The pixel array defined in claim 6, wherein the first pixel is covered by a green color filter element, wherein the second pixel is covered by a blue color filter element, wherein the third pixel is covered by a red color filter element, and wherein the fourth pixel is covered by a green color filter element.
 8. The pixel array defined in claim 1, wherein each inner sub-pixel group comprises first and second inner sub-pixels that are configured to generate phase detection data.
 9. The pixel array defined in claim 8, wherein the first and second inner sub-pixels of the first pixel have the first orientation and wherein the first and second inner sub-pixels of the second pixel have the second orientation.
 10. The pixel array defined in claim 8, wherein the first and second inner sub-pixels of the first pixel have the second orientation.
 11. The pixel array defined in claim 1, wherein the repeating unit cell of two-by-two pixels further comprises: a first shielding layer that covers a first half of the inner sub-pixel group of the third pixel; and a second shielding layer that covers a second half of the inner sub-pixel group of the fourth pixel.
 12. A pixel array comprising a plurality of pixels, wherein each pixel of the plurality of pixels has a structure that follows a pattern, wherein the pattern comprises a repeating unit cell of two-by-four pixels that is repeated across the pixel array, and wherein the repeating unit cell of two-by-four pixels comprises: a first two-by-two group of pixels, wherein the first two-by-two group of pixels includes an upper left pixel, an upper right pixel, a lower left pixel, and a lower right pixel that each have first and second outer sub-pixels and a inner sub-pixel group nested within the first and second outer sub-pixels and wherein the first and second outer sub-pixels in the first two-by-two group are arranged in a respective orientation and are configured to generate phase detection data; and a second two-by-two group of pixels that is adjacent to the first two-by-two group of pixels, wherein the second two-by-two group of pixels includes an upper left pixel, an upper right pixel, a lower left pixel, and a lower right pixel that each have first and second outer sub-pixels and an inner sub-pixel group nested within the first and second outer sub-pixels, wherein the first and second outer sub-pixels in the second two-by-two group are arranged in a respective orientation and are configured to generate phase detection data, and wherein the orientations of the pixels in the second two-by-two group of pixels are different than the orientations of the pixels in the first two-by-two group of pixels.
 13. The pixel array defined in claim 12, wherein the upper left pixel in the first two-by-two group of pixels has first and second outer sub-pixels arranged in a first orientation, wherein the upper left pixel in the second two-by-two group of pixels has first and second outer sub-pixels arranged in a second orientation, wherein the upper right pixel in the first two-by-two group of pixels has first and second outer sub-pixels arranged in the first orientation, and wherein the upper right pixel in the second two-by-two group of pixels has first and second outer sub-pixels arranged in the second orientation.
 14. The pixel array defined in claim 13, wherein the lower left pixel in the first two-by-two group of pixels has first and second outer sub-pixels arranged in the second orientation, wherein the lower left pixel in the second two-by-two group of pixels has first and second outer sub-pixels arranged in the first orientation, wherein the lower right pixel in the first two-by-two group of pixels has first and second outer sub-pixels arranged in the second orientation, and wherein the lower right pixel in the second two-by-two group of pixels has first and second outer sub-pixels arranged in the first orientation.
 15. The pixel array defined in claim 14, wherein first and second outer sub-pixels arranged in the first orientation are horizontally adjacent and first and second sub-outer pixels arranged in the second orientation are vertically adjacent.
 16. The pixel array defined in claim 14, wherein the first orientation and the second orientation are orthogonal.
 17. The pixel array defined in claim 12, wherein the upper left pixel in the first two-by-two group of pixels has first and second outer sub-pixels arranged in a first orientation, wherein the upper left pixel in the second two-by-two group of pixels has first and second outer sub-pixels arranged in a second orientation, wherein the upper right pixel in the first two-by-two group of pixels has first and second outer sub-pixels arranged in the second orientation, wherein the upper right pixel in the second two-by-two group of pixels has first and second outer sub-pixels arranged in the first orientation, wherein the lower left pixel in the first two-by-two group of pixels has first and second outer sub-pixels arranged in the second orientation, wherein the lower left pixel in the second two-by-two group of pixels has first and second outer sub-pixels arranged in the first orientation, wherein the lower right pixel in the first two-by-two group of pixels has first and second outer sub-pixels arranged in the first orientation, and wherein the lower right pixel in the second two-by-two group of pixels has first and second outer sub-pixels arranged in the second orientation.
 18. The pixel array defined in claim 12, wherein the upper left pixel in the first two-by-two group of pixels and the upper left pixel in the second two-by-two group of pixels are both covered by respective color filter elements of a first color, wherein the upper right pixel in the first two-by-two group of pixels and the upper right pixel in the second two-by-two group of pixels are both covered by respective color filter elements of a second color, wherein the lower left pixel in the first two-by-two group of pixels and the lower left pixel in the second two-by-two group of pixels are both covered by respective color filter elements of a third color, and wherein the lower right pixel in the first two-by-two group of pixels and the lower right pixel in the second two-by-two group of pixels are both covered by respective color filter elements of a fourth color.
 19. A pixel array comprising a plurality of pixels, wherein each pixel of the plurality of pixels has a structure that follows a pattern, wherein the pattern comprises a repeating unit cell of two-by-two pixels that is repeated across the pixel array, and wherein the repeating unit cell of two-by-two pixels comprises: first, second, third, and fourth pixels, wherein each pixel comprises first and second sub-pixels that are configured to generate phase detection data, wherein the first and second sub-pixels are the only sub-pixels formed in each pixel, wherein the first and second sub-pixels of the first pixel have a first orientation, and wherein the first and second sub-pixels of the second pixel have a second orientation that is different than the first orientation.
 20. The pixel array defined in claim 19, wherein the second orientation is perpendicular to the first orientation. 